This disclosure relates generally to electrical devices and, more particularly, to an adaptor for a light bulb socket.
Electrical and electronic devices are subject to stringent safety standards. Generally, in order to be marketed, an electrical device must be shown to comply with protocols established by an independent testing agency (e.g., Underwriters Laboratories in the United States). The major exception to this principle are light bulbs, which are still manufactured and used in a form virtually unchanged since Edison""s time. For over 130 years, the vast majority of light bulbs manufactured and sold in the United States have employed threaded or xe2x80x9cEdisonxe2x80x9d sockets, even though these sockets are recognized to constitute a shock hazard. Even the so-called bayonet socket, developed later, provides some risk of electrical shock during the process of light bulb replacement. Although in recent years, shockproof connectors employing pin bases have been provided for some types of fluorescent lamps, these systems have not been universally adaptedxe2x80x94not in the United States nor in the rest of the world.
This situation persists, notwithstanding the recommendations of a committee of international testing agencies, acting worldwide, which has been in existence for 22 years, and has developed suggestions and guidelines for future designs of shockproof base socket systems. So far, however, with one exception (U.S. Pat. No. 6,033,249), no design has been presented which would satisfy all conditions or stipulations of the so-called xe2x80x9crequirement catalogxe2x80x9d adopted by this committee.
The important condition which says that lamps with xe2x80x9cnewxe2x80x9d bases must be insertable into approximately 60 billion existing lamp sockets by means of an xe2x80x9cadaptorxe2x80x9d is hard to satisfy, in particular because of a further requirement saying that such adaptor, after having been screwed into the socket, should be impossible to screw out of the socket without a special tool.
This task is solved by the present invention by designing the outer thread of the adaptor as a loose threaded, electrically conductive bushing and arranging it on the adaptor body in an easily rotating manner.
By means of a bolt, designed similarly to a key, the rotating threaded bushing can be connected rigidly with the adaptor body, and the adaptor body can then be screwed into the thread of the Edison socket. The rigid connection can be achieved either by providing holes and ribs in the threaded bushing, which are engaged by the xe2x80x9ckeyxe2x80x9d, or by providing a wedge which simply wedges together the outer thread with the adaptor body by means of a key.
After inserting the adaptor, the key is taken out, the threaded bushing is freely rotating again and the lamp may be inserted into the adaptor, but the lamp cannot be xe2x80x9cscrewed outxe2x80x9d out of the socket anymore; it can only be xe2x80x9cpulled outxe2x80x9d from the pin socket.
The adaptor is advantageously equipped with a shockproof pin contact system, for example, apparatus according to the aforementioned U.S. Pat. No. 6,033,249 (the text of which is hereby incorporated by reference herein) or a similar system. An advantage of pin contact systems is that the electrically xe2x80x9chotxe2x80x9d contacts are recessed to prevent incidental bodily contact when inserting or removing light bulbs.
Another advantage of the invention is that different threaded bushings can be put on the adaptor body, so that the same adaptor body can be used with E27 threads for Europe or with E26 threads for America, for example.
Thus, the present invention provides a socket assembly which can be screwed into a conventional Edison socket to retrofit the Edison socket assembly for use with lamps (light bulbs) having pin connectors.
Although certain apparatus constructed in accordance with the teachings of the invention have been described herein, the scope of coverage of this patent is not limited thereto. On the contrary, this patent covers all embodiments of the teachings of the invention fairly falling within the scope of the appended claims either literally or under the doctrine of equivalents.